The long-term goal of the principal investigator is to enter into the field of microbial pathogenesis. The research and training program outlined in this proposal is designed to efficiently facilitate this transition. The research proposal is based on a highly tractable experimental system that will provide experience in microbial genetics, comparative genomics and in vivo assessments of bacterial-host interactions. Targeted coursework, seminars, journal clubs, group meetings, participation in national meetings and strategic collaborations will supplement laboratory research to provide a comprehensive training program. For the past several decades, the field of microbial pathogenesis has focused almost exclusively on understanding the roles of virulence factors in colonization and disease. The physiology of pathogenic bacteria has been relatively unexplored and the career transition outlined here will be advantageous to both the applicant and the field. The proposed research focuses on understanding interconnections between energy metabolism and virulence using Bordetella species as model organisms. Previous biochemical analysis by another laboratory established that virulent and avirulent Bordetella strains contain different types of cytochrome oxidases. This suggests that cytochrome oxidase synthesis is regulated, however, the implication for virulence is unknown. The PI plans to systematically investigate the relative contributions of cytochrome oxidases to the infectious cycle. In Aim 1, a comprehensive expression profile of all cytochrome oxidase genes will be conducted to characterize virulencedependent and -independent mechanisms of regulation. In Aim 2, deletion and ectopic expression mutants of the cytochrome oxidases will be generated and characterized. The relative contributions of cytochrome oxidase to the infectious cycle will be analyzed in Aim 3 using high-resolution animal models of respiratory tract infection.